Mustache appears to encode everything parsed through it as a {{variable}} but I don't want this to happen. How do I stop it in an instance of mustache? I don't want to break core code.

Your first option for doing variable interpolation without HTML escaping is to use either the triple mustache {{{unescapedInterpolation}}} tag (or its alternate-delimiter-friendly equivalent, {{&unescapedInterpolation}}).

It is often said of Lua that it does not include batteries. That is because the goal of Lua is to produce a lean expressive language that will be used on all sorts of machines, (some of which don’t even have hierarchical filesystems). The Lua language is the equivalent of an operating system kernel; the creators of Lua do not see it as their responsibility to create a full software ecosystem around the language. That is the role of the community.